Sealing system for exhaust-gas lines

ABSTRACT

A sealing system, in particular for sealing multiple-part exhaust-gas lines for an internal combustion engine, having at least a first ( 9 ) and a second flange part ( 11 ) which guides a flow of heat ( 5 ), which flange parts ( 9, 11 ) delimit a receiving space ( 33 ) for at least one sealing element ( 39, 31 ) between them, is characterized in that the flange parts ( 9, 11 ) which adjoin one another in each case form an outwardly projecting annular flange ( 13 ) which faces away from the flow of heat ( 5 ), extends transversely with respect to the former and in which the mutually adjacent end faces ( 15, 17 ) of the flange parts ( 9, 11 ) form at least partial chambering of the receiving space ( 33 ) of the sealing element ( 29, 31 ) which lies in a radially outwardly lying end region of the flange parts ( 9, 11 ) in relation to the flow of heat ( 5 ), and in that the radially outwardly open receiving space ( 33 ) is delimited axially by the adjacent end faces ( 15, 17 ) of the flange parts ( 9, 11 ) and radially to the inside by an insert element ( 35, 39 ) which is situated between the flange parts ( 9, 11 ).

The invention relates to a sealing system, in particular for sealing of multipart exhaust-gas lines for an internal combustion engine, having at least one first and one second flange part which conduct a heat flow and which between themselves delimit a receiving space for at least one sealing element.

Sealing systems of this type are known. DE 10 2004 060 845 A1 shows, for example, such a sealing system for the exhaust gas line of a reciprocating piston engine, the sealing element being a metallic gasket in the form of a profile body with a C-shaped profile cross section. Sealing elements on the exhaust gas line are subject to very high temperatures which can exceed 600° C. Even if materials are used with properties that are suitable with respect to heat resistance, the sealing elements at the prevailing high operating temperatures lose their functional properties which are required for sealing, especially the elasticity of the sealing elements is reduced by creep processes due to overly high thermal loads.

Accordingly, the object of the invention is to provide a sealing system which, when used in a hot gas region, ensures reliable sealing even when high temperatures occur on the exhaust gas lines to be sealed.

According to the invention, this object is achieved by a sealing system which has the features of claim 1 in its entirety.

In that, as specified in the invention, for the sealing element there is chambering in an annular flange which, facing away from the heat flow, projects to the outside, the flange parts themselves form thermal shielding relative to the heat flow, especially since according to the invention the receiving space is located in the radially outside-lying end region of the flange parts. In that the receiving space is delimited radially to the inside, in addition, by an insert element which has been inserted between the flange parts, the sealing element is shielded especially effectively against the heat flow such that the sealing system according to the invention can also be reliably used on exhaust gas lines which are thermally highly loaded.

For example, a metallic fire ring can be used as the insert element which acts as the thermal barrier between the inner heat flow and the receiving space of the sealing element.

Alternatively, for especially advantageous embodiments, there can be an insert element of a material with correspondingly low thermal conductivity, in particular of a nonmetallic material which can form an especially effective thermal barrier.

In especially advantageous embodiments, for this purpose there is an annular body of ceramic fiber material such as amorphous aluminum silicate fibers or of crystalline aluminum oxide fibers. Alternatively, there could also be a modern composite material.

Preferably the sealing element which has been chambered in the receiving space is a metallic, molded ring seal, or metal bead seal.

The clamping means which braces the flange parts to one another can be a clamping ring, and the arrangement can advantageously be such that the clamping ring overlaps the radially outer, open side of the receiving space and thus completes the chambering of the sealing element.

When the sealing element is a molded ring seal, it can have preferably a C-shaped or V-shaped profile cross section, the molded ring seal preferably being installed in the receiving space such that the C-profile is open radially to the inside. Furthermore, it is possible to provide the sealing element with a meandering profile cross section, instead of a V-shaped or C-shaped profile cross section, in the manner of a bellows solution in which several folds lying on top of one another form the cross section.

In any case, for the respective sealing element the invention forms thermal protection so that for metallic sealing elements of a material which is available for high temperature use reliable sealing in hot gas regions is ensured. The annular shape for the sealing element can be circular or nearly circular. Furthermore, ring shapes are conceivable in the form of an oval or a rectangular shape, preferably with rounded corner regions.

The invention is detailed below using embodiments shown in the drawings.

FIG. 1 shows a longitudinal section of adjacent line sections of an exhaust gas line, drawn highly schematically simplified, broken away and half-side, the line sections being mutually sealed by a sealing system according to one embodiment of the invention, and

FIG. 2 shows a longitudinal section of a second embodiment of the sealing system, similar to FIG. 1.

In the figures, a first line section and a second line section of an exhaust gas line are designated as 1 and 3. In the operation of the pertinent internal combustion engine, the exhaust gas line conducts an exhaust gas-heat flow 5 with a correspondingly high exhaust gas temperature. The line sections 1 and 3 which are to be sealed against one another by means of the sealing system according to the invention and which are to be connected to one another each have a flange part 9 and 11 respectively which projects radially to the outside relative to the axis 7 of the line. The flange parts 9 and 11 together form an annular flange 13, the flange parts 9 and 11 having end faces 15 and 17 which face one another. In order to connect the line sections 1 to one another, the flange parts 9, 11 of the annular flange 13 are braced to one another by suitable clamping means, of which the figures show clamping means of a conventional type, in highly schematic form, in FIG. 1 clamping rings 19 with a screw fitting 21 and in FIG. 2 a clamping ring 27 which has been pulled onto the bevels 25 of the flange parts 9 and 11 being shown.

FIG. 1 shows for the seal between the flange parts 9 and 11 a two-layer metal bead seal 29, while in the example of FIG. 2 a metallic molded ring seal 31 with a C-shaped profile cross section is shown. In any case, the pertinent sealing element is at least partially chambered in a receiving space 33 formed between the flange parts 9 and 11. In the example of FIG. 1 the receiving space which is open on the outer peripheral side on the annular flange 13 is delimited axially by the end faces 15 and 17 of the flange parts 9 and 11 and delimited radially to the inside by the insert element which in the example of FIG. 1 is a metallic fire ring 35 which is inserted between the flange parts 9 and 11 and which delimits the receiving space 33 with its radially outside-lying annular edge 37.

The example of FIG. 2 conversely differs, aside from a different type of clamping means (clamping ring 27), mainly in that instead of a bead seal 29 a molded ring seal 31 is installed in the receiving space 33 and that instead of the fire ring 35 a nonmetallic insert element is inserted between the flange parts 9 and 11, specifically, an annular body 39 of a material with poor thermal conductivity. The materials for this purpose can be, for example, among other things, ceramic fiber materials such as amorphous aluminum silicate fibers or of crystalline aluminum oxide fibers, or any materials which form effective heat shielding between the heat flow 5 and receiving space 33. The insert element can also consist of a modern composite material, for example, formed from metallic and nonmetallic materials which ensure good heat shielding in the pertinent connection. 

1. A sealing system, in particular for sealing of multipart exhaust gas lines for an internal combustion engine, having at least one first (9) and one second flange part (11) which conduct a heat flow (5) and which between themselves delimit a receiving space (33) for at least one sealing element (29, 31), characterized in that the flange parts (9, 11) which are respectively adjacent to one another form an annular flange (13) which projects to the outside, which faces away from the heat flow (5), which runs transversely to the latter, and in which the adjacent end faces (15, 17) of the flange parts (9, 11) form at least partial chambering of the receiving space (33) of the sealing element (29, 31) which, relative to the heat flow (5), is located in the radially outside-lying end region of the flange parts (9, 11), and that the receiving space (33) which is open radially to the outside is axially delimited by the adjacent end faces (15, 17) of the flange parts (9, 11) and radially to the inside by an insert element (35, 39) which is located between the flange parts (9, 11).
 2. The sealing system according to claim 1, characterized in that the insert element is a metallic fire ring (35).
 3. The sealing system according to claim 1, characterized in that there is an insert element (39) consisting of a material with low thermal conductivity.
 4. The sealing system according to claim 3, characterized in that the insert element is an annular body (39) of ceramic fiber material such as amorphous aluminum silicate fibers or of crystalline aluminum oxide fibers, or of a composite material.
 5. The sealing system according to claim 1, characterized in that the sealing element is at least one molded ring seal (31).
 6. The sealing system according to claim 1, characterized in that the sealing element is at least one metal bead seal (29).
 7. The sealing system according to claim 1, characterized in that the clamping means for bracing the flange parts (9, 11) is a clamping ring (19, 27) which overlaps the radially outer, open side of the receiving space (33). 